Electrical resistance-furnace.



OTTOKAB 'SERPEK, OF PARIS, FRANCE,

PATENT osnicn.

ASSIGNOR TO SDCIETE sense ess nee I ni'rnunn's, on PARIS, seems.

' RESISTANCE-FURNACE.

I Specification ef Application filed June 21,

Ta all wh'omjt may cemei'n."

' 7 Be it known that I, QTTOKAR' Seemin a reaction so that in the balance the sub i stance .obtmnecl contains principally earh gle subject of the Emperor of Austria-Hungary,

and a resident of '12 Rue Roquepine, Paris, France, have invented newend useful Improvementsin Electrical Resistance Furnaces, of which cation.

This invention relates to electrical resist ance furnaces intendecl especially for the manufacture 0f aluminium nitrid. 'It is well known that if aluminium be brought in presence of carbon tn a; hig. ten' perature, it can fix or 'combine with nitrogen so as to give rise to; aluminium niti icl. llloreover, experiments have shown that to obtain this reaction under the best conditions possible, it is necessary to operete at hightempemtures which are nevertheless lower than those t which the fo mw t'ion of .carhid would become. possible, namely in the neighhorhoodvol. .1800 C. In spite of th'e knowledge of these facts serious? clifliculties-have been encountered hitherto. in the attempt to carry out this mainline the follnwing is a specifiture, for Want 0:11 haying used an. apparatus which allows of ohtainingthe, suitable .tem-. peratuie and of distributing it uniformly over the whole -of the mass-under treat ment. Electrical arcfurnaces or those with a resistance consisting of the actual mass under treatment, the only ones employed hitherto, are found to afford only. a very ir i'egular distribution oilheat; the tenipern--; tureiis too high in certain zones where the current elects to pass, While the rest of the mass is .at too low a tempeimtu 'e;' c0nsequently there is formed in the over heated arts a stratum of carloicl, which can only with cliiiiculty be decomposed and forms an obstacle to the propagation of the desired portionsofnitrids; The present invention has now for object the applicationto this.inanufaeture of e. rotary" resistance furnace in which the re sistance no longer consists of the actual new t'erialtreated, but is independent thereof; it consists either of tube or of a" series of rectilinear, heliceiclal or other bars, fitted into the.eesing. ef the furnaces and extending for its entirelength; thex esistances are connected at .e h -.end to the terminals of more or less pure, mixed with a isinall prof;

Letters latent.

Patented Nov. '19, 1812. 1914;. Serial No. 568,158.'

theelectricel supply. The furnace is in the fennel? a hollow cylinder or. tube open at lilS opposite ends anal preferehlv slightlv inclinetl so as to feed slowly fOll fflitl l'lfie ma ing to the present invention.

In this drawingfl igurel represents two half cross-sections oneof the central part 01'? the furnace -and the other nemone end. Figs. 2, 3 and Se -e transverse sections et' modifications of the furnace in which the -Fig. al' is a longitudinal section of the modificatlonrepresented in Fig. 3, the section being taken on-linef ll oi. that figure. Fig. "6 is a section of the modification. repure. "Fig. 7 pepresents a modified form hf 'ful'nace, showing a suitable sliirring device v or'ineans for conveying the current; in this figure the furnace re 'neseuted one half in end View the otherin section alone; line 7.7 of Fig. 8. l igl 8 represents in section upon line E-'5S of Fig. 7 the si-mm of the furnace adjacent to the with Fig. 9 represents in a. similar nmnneiu law-(lilicatien of the slipaingi.

'llie furnace consists ofun' eXiei-ioi cote-2' .A -oi?sheet-him 'or the like provideil inter 'nnlly with l'flfl{l('l()l"\" llllCliS l). 'l pmi this first lining; placed :1 second C l'mfiu'ml elf agglomerated nitr'itl. The'chief sulistnnces e refrnctmy anti insulnting nnhii'e'gqiiei lly used can hardly be employed here either because theyv are attacked .hy the llliiiillfiii under treatment onbeeauseht the high temperatures at xvhich the operation takes place they are softened or at least undergo some contraction which tends to loosen the in'iateriul. w h

. [In the secnncl lining (3 nre litteci. resist- :inces E extending; for the whole length of the furnace anclprojecting Within the centralcylintlri'cel part of the furnace in which are placed the materials in he treated. When thEfUHlERCQ res-elves, these materials terial under treatment Whichis in this we resistances have been given different shapes.

i esentetl in Fig. 5. on line 6--'6 of that fie? lee taining the same surface of contact for the.

material under treatment with a small cross-section and likewise a smaller fitting surface in the refractory lining. Moreover, instead of using several resistances a single one may be used covering the whole interior of the furnace in the form of a tube of circular or suitable polygonal section, as represented in Figs. 3.and 4. Within this resist ance-forming tube a number of projections may be arranged to-efi'ectthe stirring of the materials and prevent them from merely sliding upon the wall of the tube. Lastly, Figs. 5 and 6 represent another arrangement which may be used; the resistances are arranged helically, each helix being composed of resistance-elements e simply juxtaposed, so that the current passes by mere contact. This arrangement allows the progress of the material in the furnace to be accelerated or retarded according to the pitch and the direction of the helices.

The resistances consist of a mixture in suitable proportions of carbon and aluminium nitrid (say 60% to 80% aluminium fi nitrid to 40% to 20% carbon) and at each extremity they are fitted in holders F of carbon to which the current may be led by brushes or the like in any suitable manner, for example the arrangement shown in Figs. 7, 8 and 9 may be employed.

The carbon cap F into which the resistances are fitted, extends as far as the sheetiron casing and carries upon its periphery a certain number of prolongations f resem bling teeth and projecting from the furnace through openings formed in the casing A.

All these teeth are connected. externally by a metal ring G, which is itself provided upon its exterior surface with a groove into which there passes a metal wire H fixed at its ends by means of spring 71 to a bar I to which the current is led in any suitable manner. As the furnace revolves, the bar I remaining always horizontal, the cable H slips upon the metal ring G, in this way passing current to the latter and so to the carbon cap F.

Instead of atable, a number of strips of metal foil G qnay be employed as shown in Fig. 9; these strips are arranged in a similar manner to the cable, the semicircular section of the groove being replaced by a rectangular section. This arrangement presents the advantage of increasing the area of the contact surfaces. For the same reason the anchoring points of the cable or of the foil strips may be brought together, so as to provide contact surface for more than a semi-circumference.

Of course the use of this furnace is not limited only to the manufacture of aluminium nitrid and it can be applied to the manufacture of other nitrids and in general to any reaction which requires a high temperature and a reducing atmosphere.

Claims- 1. A rotary electric resistance furnace, comprising a tubular furnace chamber open at its opposite ends for the continuous passage of the material to be treated as the furnace rotates, resistance elements embedded in the refractory lining at the interior of the furnace to come into contact with said material and means for leading electric current to the resistance elements.

2. A rotary electric resistance furnace,

comprising a tubular furnace chamber and resistance elements extending lengthwise of said chamber and embedded in the refractory lining and projecting into the chamber to form a stirrer, in combination with means for leading an electric current thereto.

3. A rotary electric resistance furnace, comprising a tubular furnace chamber and resistance elements in the form of hollow bars extending lengthwise of said chamber and embedded in the refractory lining, in combination with means for leading an electric current thereto.

4. An electric resistance furnace, having a refractory lining and resistance elements carried thereby and she ed to form stirrers.

In testimony whereo I have signed my name to this specification, in the presence of two subscribing witnesses.

I OTTOKAR SERPEK.

Witnesses:

CHARLES DONY, JACQUES SIGOURNEY. 

